Acamptonectes.
Acamptonectes is a genus of ophthalmosaurid ichthyosaur, a type of dolphin-like marine reptile that lived during the Early Cretaceous around 130 million years ago. The first specimen—a partial adult skeleton—was discovered in Speeton, England, in 1958, but it was not formally described until 2012. Acamptonectes had unusual adaptations that made its trunk rigid, including tightly-fitting bones in the occiput (back and lower part of the skull) and interlocking vertebral centra, likely allowing it to swim at high speeds with a tuna-like form of locomotion. Other distinguishing characteristics include an extremely slender snout and unique ridges on the basioccipital bone of the braincase. As an ichthyosaur, Acamptonectes had large eye sockets and a tail fluke. Its teeth, which were slender and textured with longitudinal ridges, were probably adapted for impaling prey such as squid and fleshy fish.
